nfsd4: fix crash on writing v4_end_grace before nfsd startup

Anatoly Trosinenko reports that this:

1) Checkout fresh master Linux branch (tested with commit e195ca6cb)
2) Copy x84_64-config-4.14 to .config, then enable NFS server v4 and build
3) From `kvm-xfstests shell`:

results in NULL dereference in locks_end_grace.

Check that nfsd has been started before trying to end the grace period.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2018-11-27 15:54:17 -05:00
parent b8db159239
commit 62a063b8e7
1 changed files with 2 additions and 0 deletions

View File

@ -1126,6 +1126,8 @@ static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t size)
case 'Y':
case 'y':
case '1':
if (nn->nfsd_serv)
return -EBUSY;
nfsd4_end_grace(nn);
break;
default: